\section{一种含永磁的轴对称接触器描述}\label{description}
%A contactor with permanent magnet actuator is a novel electromagnetic device, which combines solenoid with permanent magnet achieving the function of operation. It is a bistable equipment and works very similar to the traditional contactor. It still operates by the principle of electromagnetics, however, its status is retained after power off with the help of permanent magnet. Therefore, this kind of contactor avoids certain drawbacks of traditional electromagnetical contactor and it can work with high reliability, small power consumption, and ability of anti-vibration.
含有永磁的接触器是一种新式的电磁设备，它将电磁螺线管与永磁体结合起来来实现操作功能。它是一种双稳态的设备，与传统的接触器具有很大的相似性。它仍然是采用电磁原理来完成动作的，但是，当断电之后，它仍能通过永磁体的作用来保持它的位置状态。因此，这种接触器避免了一些传统电磁接触器的缺点，它具有高可靠、节能、抗振性等优点。

%As shown in Fig. \ref{model}, it is a typical DC axisymmetrical contactor prototype with permanent magnet actuator which has a weight of 0.45 kg and a size of 75 mm $\times$ 55 mm $\times$ 79.1 mm. It mainly consists of metal cover, plastic cover, sleeve, iron core (material: DT4E), permanent magnet (NdFeB), coil, armature, non-magnetic shaft (stainless steels), and so on.
如图 \ref{model}所示，为一个典型的含永磁直流轴对称接触器。重 0.45 kg，大小为 75 mm $\times$ 55 mm $\times$ 79.1 mm。它的结构主要包含金属外壳、塑料外壳、套筒、铁芯（材料：DT4E）、永磁体（NdFeB）、线圈、衔铁、非导磁连接杆（不锈钢）等等。
\begin{figure*}[t]
\centering
        \subfigure[接触器外观]{
            \label{view45} %% label for first subfigure
            \includegraphics[width=4.cm]{view45}}
        \hspace{2mm}
        \subfigure[剖面图]{
            \label{assemble1} %% label for second subfigure
            \includegraphics[width=4.7cm]{assemble1}}
        \subfigure[简化模型]{
            \label{simple2} %% label for first subfigure
            \centering{\includegraphics[width=3.5cm]{simple2}}}
        \hspace{2mm}
        \subfigure[有限元计算模型]{
            \label{bd} %% label for second subfigure
            \centering{\includegraphics[width=3.5cm]{bd}}}
    \caption{含永磁轴对称接触器结构及建模
     (1-非导磁连接杆. 2-金属外壳. 3-上线圈. 4-衔铁. 5-永磁. 6-铁芯. 7-下线圈. 8-塑料外壳.)}
    \label{model} %% label for entire figure
\end{figure*} 